The present invention relates to obtaining an electrophotographic photoreceptor by continuously coating liquid photosensitive material on the circumferential surfaces of a plurality of cylindrical drums, and to a manufacturing method for the electrophotographic photoreceptor drum.
As a method for manufacturing an electrophotographic photoreceptor by coating a photoreceptor solution onto the outer surface of a cylindrically formed drum, a spray coating method, a dip coating method, a blade coating method, a roll coating method, etc., are previously known.
On the other hand, a slide hopper coating method for coating a photoreceptor solution onto the circumference of a cylindrical drum by moving a scraper blade located around the drum, with a certain clearance with respect to a drum surface, has been proposed in Japanese Patent Publication Open to Public Inspection No. 15866/1981, and Japanese Patent Examined Publication Nos. 72350/1991 and 7265/1994.
Further, a continuous coating method in which a connecting member is provided on a cylindrical drum, or a continuous coating method in which no connecting member is used, has been proposed in Japanese Patent Publication Open to Public Inspection Nos. 242165/1989, 118866/1991, 118867/1991 and 274564/1991.
Further, as an improved method of the above proposals, an apparatus for coating a photosensitive solution onto the outer surface of a cylindrical drum is proposed in Japanese Patent Publication Open to Public Inspection No. 189061/1983. That apparatus comprises: a coating solution distribution slit formed continuously around the outer peripheral surface of the cylindrical drum; a solution slide surface, formed continuously inclined toward the lower side of the outlet for the coating solution of the coating solution distribution slit, the solution slide surface having an end portion, the diameter of which is slightly larger than that of the outer periphery of the cylindrical drum; and a lip-shaped portion extending from the end portion of the slide surface to the lower portion of the apparatus.
Further, conventionally, as to the shape of the electrophotographic photoreceptor, there are a sheet type photoreceptor and a cylindrical drum type photoreceptor. In the sheet type photoreceptor, a photosensitive solution is coated onto a resin film or aluminum foil by methods such as roll-coating, bar-coating, knife-coating, or blade-coating, etc. In the cylindrical drum type photoreceptor, a photosensitive solution is coated onto the cylindrical drum surface formed of stainless steel, aluminum, copper, brass, or plastic material, and as a coating method, a bead-coating method is proposed which has a slide surface represented by the method disclosed in Japanese Patent Publication Open to Public Inspection No. 189061/1983.
In the above-described spray-coating method, solvents included in a photosensitive solution are evaporated before the photosensitive solution jetted from a spray gun reaches the outer surface of the object to be coated, and dried particles adhere onto the surface of the object to be coated. Accordingly, a coated surface having the required smoothness can not be obtained, and controlling the film thickness of the photoreceptor layer is difficult. Further, in the blade-coating method and roll-coating method, a uniform coating film can not be obtained due to the viscosity of the coating solution, which is a disadvantage. Still further, in the dip-coating method, surface smoothness of the coating film, and uniformity of the coating film, described above, are improved, however, the film thickness depends on the physical properties of the coating solution and the coating speed. Accordingly, adjustment of the coating solution is very important, however, this adjustment is very difficult in practice. Further, the coating speed is slow, resulting in lower productivity.
Normally, cutting is performed on the end surface of the cylindrical drum of the object to be coated. At the cutting portion, disturbance of the coating solution occurs just below the portion joined to the following cylindrical drum, resulting in non-uniformly coated film and further loss of beads, which is disadvantageous.